Nearly one year ago, four Dallas Police Department officers and a Dallas Area Rapid Transit officer were killed in an ambush that also injured several other local officers. It has been reported that a critical piece of former Army veteran Micah Johnson's motivation was his anger over the tragic killings of several African-American men at the hands of white police officers around the country.

If we are to try to make sense of the Dallas ambush and the terrible events that precipitated it over the years, it is important to know how often and why police use force. We also must better understand the frustrations perceived and experienced by communities and police.

Let's start with some facts about use of force, because what we think we know may not be accurate.

• Use of force includes a wide range of actions.

The use-of-force continuum starts with low levels of force (verbal commands) and escalates to middle levels (holds) to intermediate (Taser deployment), and finally to the most extreme and potentially fatal use of force (firearm discharge). The most severe types of force are used the least frequently.

• Most officers do not plan to use deadly force.

Yet, sometimes police encounter citizens in difficult circumstances, and officers must make instantaneous decisions without having all the information necessary. It is much like when a baseball umpire needs to make a call on a ball or strike. Time is not on the umpire’s side. Officers cannot hit pause to go read a manual or look at a replay. I don't mean to trivialize these decisions, but to highlight their complexity.

• Various factors influence when police use force and the severity of force.

These include a crime in progress, citizens under the influence of alcohol or drugs, the presence of bystanders, and the citizen’s general behavior. Officer characteristics are related to use of deadly force, too. My colleagues and I found in a new study in Police Quarterly that officers who had difficulty in controlling their impulses were more likely to discharge their firearms.

• Estimates reported by the National Law Enforcement Officers Memorial Fund show that, with the exception of 2011 and the 9/11 attacks, the number of officer fatalities has been steadily decreasing since the early 1970s.

In 2016, 135 officers were killed in the line of duty out of more than a million officers nationwide. Despite what some commentators have argued, researchers have found no increase in assaults against police after the death of Michael Brown in Ferguson, Mo., in 2014 and little empirical evidence to support claims that police have stepped back from their duties.

We still have much to learn about the use of force, including the subtler context of the community's interaction with the police, especially from the perspectives of the community members, including minority communities.

It may be time to get past divisive views that cops are running rampant using force or that citizens hate cops, as neither narrative is constructive or based in factual evidence. Social control depends upon citizens and officers trusting and working with one another to keep our cities safe.

As with most organizations, police departments need to recruit a diverse and qualified workforce and provide rigorous training on how to de-escalate situations and recognize their own implicit bias. Body-worn cameras, civilian review boards, and transparency of data also help reduce the use of force and increase trust and accountability.

And above all else, if officers are found to have violated policy, then they should be reprimanded and punished accordingly.

Perceptions about police and citizens should be based on the most accurate and available of information. Anything less would be a shame.

Alex R. Piquero is the Ashbel Smith professor of criminology and associate dean for graduate programs at The University of Texas at Dallas. Follow him on Twitter @DrAlexPiquero or email apiquero@utdallas.edu.